This invention relates to lasers and, more particularly, to improved host crystals therefor.
Presently there are many laser systems, for military and commercial applications, which operate on the 1.06 .mu.m transition of Neodymium (Nd). Most of the present operating systems use Yttrium Aluminum Garnate (YAG) as a host crystal. The only other commercialized hosts are non-crystalline glasses, and crystals of YLF and YALO.
Because the dopant ion Nd.sup.3+ is much larger (1.04 A vs. 0.92 A in radius) than the Yttrium ion it replaces, the strain on the lattice limits the amount of Nd.sup.3+ that can be doped in without degrading the crystal uniformity. Because this limit is so low, approximately 1% substitution, most Nd:YAG is grown at the limit of dopant density.
In order to increase the limiting density of Nd.sup.3+ in YAG, attempts have been made to stretch the lattice by partially substituting Gadolinium (Gd.sup.3+) with an ion radius of 0.97 A for Yttrium. Substituting Gd.sup.3+ for Y.sup.3+ did in fact expand the lattice. However, substitution is limited to approximately one quarter of the Y.sup.3+ ions, and greater concentrations, especially 100% or complete substitution, degrade the crystal.
Accordingly, it is an object of this invention to provide an improved laser crystal.
It is a further object of this invention to provide a substitute for a Nd:YAG laser which is more efficient.